Method of removing sericin from silk



NOV- 107 1936, w. T. REDDlsH METHOD OF RMOVING SERICIN FROM SILK I `/NI/ENToR.

Original Filed Sept.`2l, 1953 BYy WM ATTORNEYS.

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atenteol Nov, EG, i936 'andere METHOD F REMOWEG SER'EN FRM SIL Warren T. Reddish, Cincinnati, idillio, assigner to Emery Industries, lino., Cincinnati, (Ehio, a cor poration of Ohio Original application September 21, i933, Serial No. 690,390. Divided and this application Tune 25, 1934, Serial No. 732,389

claims. (ci. sur.)

This invention relates to a new detergentl adapted for a multitude of processes such as home laundry use, power laundry use, degurnming silk, scouring wool, or washing textiles of any nature at any time during the progressof their fabrication and finishing.v

The invention can be best explained and understood when presented as an improvement over the subject matter of the British Patent No. 19,759, 1912, granted to Grigori Petroli. chemist, of Kuskowo, Russia. This patent refers to and must be read in the light of its companion Patent No. 19,676 of 1912. The patent in question is entitled-An improved process for manufacturing detergents, detergent solutions, or emulsions. The disclosure of this patent is admirably summarized in the first two claims, which read as follows;

1. A process for manufacturing a detergent which consists in employing the sulphonic acids extracted by means of alcohol or acetone or like solvents from sulphonated mineral oil hydrocarbons according to the process of Specification No. 19,676 of 1912 as the raw material for producing the detergent.

2. 'A process according to claim 1, for manufacturing a detergent which consists in treating the sulphonic acids either in a pure state or in admixture with fats, fatty oils, or fatty acids with caustic or carbonated alkalies or ammonia to obtain a "neutral, acid, or alkaline detergent mixture as desired.l

The specification, aswell as the claims, abounds in the use of the disjunctive and from this it may be inferred that Petroi had gone only so far as to ascertain that his sulphonates were an appropriate raw material to be used as a soap, but that he had not made any determination of how the sulphonates should be used. The most that Petroff claimed for his sulphonate is as follows:

In regard to its detergent powers, it is in nov way inferior to good brands of soap made from fat.

However, though more than twenty years has elapsed since Petroff's work and disclosure, Petroffs novel raw material has never been used either as soap or as an ingredient of soap. This raw material has however been sold to the soap makers all over the World in tremendous quantitics and has been used by them in the making o f soap as a substitute for the Well-known Twitchell reagent for the purpose of splitting fatty glyceridesinto fatty acio and glycerine. These circumstances conclusively establish the fact that either Petroli was mistaken in his notion or hope that his new raw material was anappropriate ingredient for soap, or that the utilization of his raw material asa soap ingredient was entirely beyond the slrillr of the soap makers all over the world.

The present invention comprises the selection of ingredients for a detergent including Petroff's raw material and the proportioning of them to provide a detergent far superior to those known in the past. More specifically, the detergent of this invention comprises alkali, fatty acids, and Petroif's mineral oil sulphonics, or mahogany sulphonates, as they are known in this country at the present time. While all of these materials are conventional ones in almost all soap factories, and while all of them have been used as detergents or suggested for use as detergents, still their specific functional relationships have never been understood. On this account they have never been used in combination in practice and in view of the liberal use of the disjunctive in the Petrofl disclosure, it cannot be said that they have even been suggested in combination. This functional relationship of alkali, fatty acid soap and mahogany sulphonates is so complex that it is only susceptible to explanation by diagram.

The accompanying drawing is a diagram disclosing how alkali, fatty acid soap and mahog-I any sulphonates, when used conjointly as a detergent, produce anew and superior detergent result by virtue of the fact that each ingredient in combinationv with each other ingredient provides a function not provided by any ingredient alone.

Anyone of a number of different alkalies may be employed, such as caustic soda, soda ashLbicarbonate of soda, sodium metasilicate or trisodiumphosphate.

Instead of the sodium compounds of the typel listed, the potassium compounds may be employed wherever warranted as a matter of cost.

used in standard practice varies in dierent in-A Now, `one of the distinguishing characteristics of this dustries according to the nature of the specific problem and even varies among the dierent plants in a given industry. However, the alkalinity incorporated in this new detergent substantially exceeds previous practice for each use. One reason that the greater strength of alkali can be used without injury to the fabric is that the mahogany sulphonates employed herein seem to act as inhibitors in relation to the alkali and tend to preserve the tensile strength of the fabric during the washing process.

In contrast to the British Petroff patent, which species that the sulphonate may be acid, alkali or neutral, the present detergent is characterized by the-presence of a very substantial and ponderable quantity of free alkali or potential alkali of the nature disclosed. For instance, silk is easily injured by alkali and the quantity of alkali used for degumming silk is therefore substantially less than that employed for most of the washing processes. However, even for degumming silk the detergent of this invention comprises at least 5% by weight of a very strong alkali, such as caustic soda. It is therefore to be noted that the detergent of this invention, even at its lower limit of alkalinity, carries a percentage of free alkali which distinguishes it from that lesser degree of alkalinity which is substantially equivalent in 0peration to neutral or acid solution.

In other words, Petroff specifies that his acid, neutral or alkaline soaps and soap solutions are functionally equivalent and specifies that his starting material, sulphonic acids, optionally mixed with fatty acids, may be neutralized, underneutralized or over-neutralized without affecting the detergent properties of the resulting soap.

This invention on the contrary is characterized by the presence of anywhere from one-third to twenty times the quantity of alkali necessary to neutralize the mahogany sulphonic and fatty acid content of the admixture. This detergent is not functionally equivalent to an acid or neutral detergent or to an over-neutralized detergent, but on the contrary its detergent action may be said to be dominated by the activity of the large quantity of free or potential alkali.

The fatty acid soap employed in this detergent may be of animal or vegetable origin and of any titre, the soap from fatty acids having a titre as 10W as ten having been found entirely'satisfactory. Red oil soap is entirely suitable for use in this detergent, though soaps from high titre fats, either alone or in combination with red oil soap, may be used.

One of the essential ingredients of the detergent of this invention is mahogany sulphonates. 'I'hese bodies are produced in the refining of petroleum or fractions thereof, such as lubricating stock, into medicinal white oil or the light colored technical oils. In this general process the petroleum is treated with fuming sulphuric acid or sulphur trioxide, after which the sludge settles out. Next, the oil is treated with an alkali and an aqueous alcohol solution which extracts the mahogany sulphonates, leaving the white oil or light colored technical oil as a remainder.

Mahogany sulphonates are recovered from the aqueous alcoholic solution by evaporation. This general process has frequently been referred to in the patent literature as the Petroli-Humphrey process for the reason that it is practiced under Petroif Patent No. 1,087,888 and Humphrey Patent No. 1,286,179.

There are other variations of this general process, though all of them produce sulphonic bodies which commercially are called mahogany sulphonates. Though these bodies are usually available in the form of the sodium salt of mahogany sulphonic acids, other water soluble salts such as the potassium salt may be used instead of the sodium salt when desired.

While the fatty acid soap sulphonate may be blended and mixed in practiand the mahogany cally any ratio according to the specific use for which the detergent is intended, it is recommended that the practice of using l0 to 60% mahogany sulphonates and to 40% fatty acid soap, be followed. These limits were selected arbitrarily, and while not highly critical, are provided for the purpose of instructing the skilled in the art as to the general optimum blending ratio.

As shown in the accompanying drawing, the

idea of this invention is to attack the soil on the 1 fabrics or the sericin on raw silk or the' wool grease on raw wool or the dressings used on textiles for lubrication or preservation in the course of their manufacture, with a powerful alkali.

The strong free alkali in solution attacks the saponiable dirt and as it is used up by saponication, the fatty acid soap hydrolyzes and supplies additional alkali (if necessary). The amount of alkali used likewise increases the detergency of the fatty acid soap-mahogany sulphonate mixture. Mahogany sulphonates do not hydrolyze. The fatty acid soap performs another function in conjunction with the mahogany sulphonates. Together they form a body which, in aqueous solution, has more power of suspending and emulsifylng dirt, grease, wax and soil in general than does either one of them alone. Mahogany sulphonates from American petroleums do not in general form water soluble calcium and magnesium salts. However, these sulphonates in combination with fatty acid soap do possess the property of solubilizing calcium and magnesium fatty acid soaps or mahogany sulphonates which may be formed as the result of hardness in the water employed for the washing process. This is of very great advantage and it has not been known before that the mixture of mahogany sulphonates and fatty acid soap would emulsify or suspend the calcium or magnesium soaps.

The mahogany sulphonates and alkali in combination effect the removal of foreign matter from the textile or fibre being washed without injury to the fibre. The mahogany sulphonates are themselves powerful emulsifying agents even for mineral oil. The combination of mahogany sulphonates and of fatty acid soap, suspends all types of dirt admirably.

The mahogany sulphonates accelerate the wetting out action of the detergent solution and also depress the interfacial tension between the alkaline solution and all oily, greasy or waxy soil or foreign matter on the fabric. Moreover, as before stated, the mahogany sulphonates seem to alter the speed with which the alkali attacks the soil or foreign matter as compared with the speed with which the alkali attacks the textile bre itself. This action is herein termed an inhibiting action and is a very great advantage, especially in regard to silk or wool, both of which are sensitive to alkalies.

It is therefore to be observed that the use of this detergent for purposes of the type specied provides a very rapid cleansing operation which saves usually one-half of the time normally consumed. In power laundry work the total amount of water used is reduced substantially in half. The clothes are washed much cleaner than is usual, do not tend to become gray on repeated washings, and do not become specked with traces of insoluble calcium and magnesium salts when there is hardness in the water. Moreover, the tensile strength of the fabric being cleansed does not seem to suifer to the extent it does in the processes now used, or to the extent to be expected from the increased amount of alkali. For instance, garments sent'through the usual power laundry fifteen times usually suffer a twelve to fifteen percent loss of tensile strength.

. Similar garments sent through a similar power of this invention washes fabrics cleaner and` more thoroughly than detergents previously used with less injury to the fabrics and moreover that it reduces the washing time and the consumption of materials, particularly water which is one of the large elements of expense in power laundry practice.

While it is possible to add the ,ingredients to the washing bath or textile treating bath separately, it is recommended that for most purposes.v particularly for power laundry use, the ingredients be ,pre-combined and thoroughly admixed. In regard to -the power laundry use, for

instance, the ingredients when admixed in theappropriate proportions, provide a detergent which can be used in finely divided, powdered or granulated form so that it kdissolves readily in the washer. Mahogany sulphonates and particularly mahogany sulphonates commercially available in this country, are thick, gummy, sticky bodies, very difcult'to handle, pour, measure or remove from shipping containers. The fatty acid soapsv and mahogany .sulphonates mixed are a viscous jell-like mass, diillcult to handle. If, however. two, three, five or more times the amount of dry alkali salt, such as sodium carbonate, be mixed with the mahogany sulphonates and the fatty acid soap, then the detergent becomes a hard, dry body which can be reduced to finely divided or powdered form and readily shipped, handled and measured. It is recommended that the alkali bethree to iive times the weight of the soap-sulphonate admixture.

While'the preferred process of constituting this detergent is reserved for a future application, the pro-portioning of ingredients to provide the nely divided detergent, as distinguished from a jelllike detergent, is an important element of this invention. The invention and its many specific advantages can be best understood in relation to the following examples of specific uses of the detergent.

Laundry practice In modern laundry practice the ldetergents used consist of high titre fatty acid soaps and alkalies. The ratio of soap to alkali and the type of alkali used varies to some extent in different plants and also depending upon the type of soil to be removed. Ordinarily a ratio of one part of soap to one part of an alkali, consisting of sodium carbonate or a mixture of' sodium carbonates and bicarbonate or sodium silicate or sodium phosphate, has been found to. give the most satisfactory results.

It has alsoV been found that a.v preliminary treatment of cold water and alkali and possibly a small amount of soap, usually termed a break followed by a number of separate sudsing operations produces a greater detergent action for a given amount of fatty soap and alkali than if the saine quantity of soap and alkali is used in one sudsing operation. The actual washing operations are followed by a chlorine bleach '.in the case of white work) a suiliclent number of rinses to remove the last tracesof soaps, a treatment with a mild acid termed the sour to remove the last traces of soaps and alkali andl ilnally a bluing and sizing operation to improve 'the appearance and finish of the washed materials. f f

The use of a number of sudsing operations results in improved quality butonly at the expense of time of treatment and quantity ofwater requirdf We"'have foundfthatthe properties of a detergent comprising a blendof fatty acid soaps and mahogany sulphonates are so different from the ordinary fatty acid soapsthat an entirely different washing procedure which results in a material saving in time and water may be employed.

This detergent is also most effective when used with much greater quantities of alkalies than have been found to be the most effective with ordinary fatty acid soaps. A quantity of alkali three to four times greater than that ordinarily.

used in laundry operations may be used without damage to the material and as a matter of fact on the average the loss in tensile strength is less than with the ordinary laundry procedure and formula.

We have found that a ratio of one part of a blendof 80% of 32 titre fatty acid soap- 20% commercial mahogany sulphonate and four parts of soda ash may be used, but one sudsing operation is required to produce work as clean if not cleaner than that produced bya multiple sudsing treatment with fatty acid soap and alkali. The number and duration of the rinses may be reduced as the detergent rinses out very easily.

The following example showing the procedure followed in washing a 250 pound load of household wash work with the fatty acid sulphonate alkali .detergent as compared with fatty acid' soap and alkali will illustrate the utility and economy of this detergent.

One badly soiled article was tornin two and half run in each load. At the completion of the washing operation itwas found that the piece washed with the fatty acid and sulphonate was 2% whiter than the piece washed with fatty soap and alkali.

Silk deaummng Raw silk consists of the truey silkv or ilbroln` covered by a coating of silk gum or sericin.A The latter is harsh, non-lustrous and somewhat unstable and must be removed in ordery that the broin may be utilized.

Sericinis attacked and rendered partially water soluble by mild alkaline solutions. This property is utilized in removing silk gum, neutralv fatty acid soaps in fairly high concentrations "'(1'` to 2%) are most commonly used both as a source of alkali, which is produced by the hydrolysis of the fatty acid soaps in water solution, and as emulsifying and dispersing agents to hold the partially solubilized sericin in solution. Fattiv acid soaps are a rather expensive source of alkali and recently small amounts of alkali have been added to the degumming baths in an effort to decrease the amount of soap required and to increase the rate of degumming. Extreme care is required in case excess alkali is used as the fibroin is also attacked by too long an exposure to alkaline solutions or by too high concentrations.

The minimum soap concentration which has been successfully employed in silk degumming is approximately 1.25% and the maximum excess alkali concentration .03%. Attempts to effect a further reduction in soap concentration or an increase in free alkalinity result either in deposition of sericin in the degumrning baths or serious weakening of the silk.

By utilizing an emulsifying and detergent mixture comprising a mixture of from 50 to 85 parts of sodium oleate and 50 to 15 parts of mahogany sulphonate, the concentration of the detergent in the degurnrning bath may be reduced to as low as .75% and the concentration of the alkali increased to as high as .065% without injury to the silk.

The following examples showing the procedure and concentrations used in degumming with red oil soap and with a blend of red oil soap and sulphonate illustrate the advantages of the fatty soap sulphonate detergent.

From the above results it will be seen that the amount of detergent can be reduced by 40% without any increases in time of degumming and without weakening of the silk.

If the concentration of the red oil sulphonate mixture is increased to 1.25% the time may be reduced to 30 minutes, resulting in a saving in time of 331/3 per cent.

Treatment of wool Wool is treated with detergent solutions either alone or in conjunction with alkalies several times in the course of manufacture. Raw wool is contaminated by dirt and earthy matter, wool grease and suint all of which must be removed to render the wool suitable for further manufacturing operations. 'I'he oils which are added to facilitate the spinning and weaving operations must be removed prior to dyeing which necessitates a second scouring operation. In the fulling operation which is carried out as a part of the final finishing operation, detergent solutions and alkalies are also used.

Wool is quite sensitive to the action of alkalies and care must be exercised in using alkalies in the scouring baths. It is also necessary to employ moderate temperatures, preferably not over 140 F. as higher temperatures cause harshening and deteriorate the fibres.

The amount of soap and the ratio of soap to alkali used in scouring raw wool varies widely depending upon the character of the wool and the nature and amount of impurities associated with it, from .25% to 1.25% soap and from 1.25 to 2.5% of soda ash being used. The relatively high soda ash content serves to saponlfy fatty acids which may be present as constituents of the wool grease.

In scouring woven fabrics for removal of the oils used in manufacture from 1.5 to 5% soap and from .5 to 2.5% of soda ash may be used, the preferred amounts depending upon the quantity of spinning oils present and their content of saponiable constituents.

In fulling approximately the same strength soap solutions are used but the alkali used is generally reduced. Alkali is necessary to exert a softening and swelling action and to accelerate the shrinkage and felting which occurs during the fulling operation.

If in place of fatty acid soap a blend of from 50 to 85% of fatty acid soap and from l5 tol50% mahogany sulphonate is used the quantity of alkali uscd in the baths may' be greatly increased without affecting the strength of the wool or harshening it or affecting its dyeing properties.

In scouring raw wool the amount of alkali may bedoubled and the Pmount of detergent decreased, the high emulsifying power of the fatty soap sulphonate blend in the presence of an appreciable alkali concentration will exert a wet ting out, cleansing and soil dispersing action even when present in a reduced amount.

In scouring piece-goods, the time of scouring and the quantity of detergent may be decreased if the mineral sulphonate fatty soap blend is used. In case the spinning oils have a high mineral oil content it is preferable to use a higher proportion of' mahogany sulphonate in the detergent blend.

The alkali content of the fulling baths may be increased and the fulling time reduced by -in creasing the alkali content. In the presence of the mahogany sulphonate and fatty detergent, the wool is ,not harshened and the wetting and penetrating powers of the solution are enhanced.

The following example illustrates the use of the mahogany sulphonate fatty soap blend as compared to the fatty soaps commonly used in scouring woolen piece-goods.

Fatty soapsulphonate Fatty mp Ratio wool to solution l to 6 l to 6.

80%;-135 titre fatty 3 oz.l per gal(i Detergent-2 oz. per gal am s' pa m. an

m95 mahogany red oilsoap -5 oz per gal sulphonate. 35 titre.

soda ash .Y 3 oz. per gal.

' soda ash. Temperature 120 F 120 F. Time 35 min 45 min.

Having described my invention, what I claim 1. The method of removing sericin from raw silk, which comprises, treating the silk bearing the sericin ,in a hot aqueous solution containing mahogany sulphonates, water soluble fatty acid soap, and caustic soda, the quantity of caustic soda employed equalling at least 5% by weight of the soap-sulphonate admixture.

2. A raw. silk degumming process,l comprising,

' treating the rawsilk in a hot aqueous bath with water soluble fatty acid soap, and an alkaline salt adapted when dissolved in water to yield a free alkali.

` .4. A process of removing sericin from raw silk,

said process, comprising, treating the raw sericin bearing silk with a` detergent in a hot aqueous solution, said detergent comprising 50 to 15% mahogany sulphonates, 50 to 85% water soluble fatty acid soap, and a quantity of an alkaline salt adapted to` yield free alkali to the extent of at least 5% by weight of the soap sulphonate mixture.

5. A solution adapted for use in degumming i raw silk in the ratio of 50 parts of solution to one part raw silk, said solution characterized by a detergent concentration of 0.75 70, said detergent'comprising water-soluble fatty acid soap and mahogany sulphonate, and a free alkali concentration of 0.65 gram NaOH per liter. WARREN T. REDDISH. 

